1. Field of the Invention
The present invention relates to a pattern forming technique for applying an application liquid containing a photo-curing material from a nozzle which moves relative to a substrate surface and irradiating light upon the application liquid to thereby form a pattern on the substrate.
2. Description of the Related Art
To form a predetermined pattern on a substrate surface, there is known a technology which requires applying an application liquid containing a photo-curing material in accordance with the shape of a pattern and irradiating the application liquid with light (which for instance may be UV light) to thereby cure the application liquid. For instance, according to the technique described in JP2010-278225A which the applicant of the present patent application has previously disclosed, the technique above is used to form a wiring pattern in a surface of a photoelectric conversion device (i.e., a solar cell). Describing in more particular details, according to this technique, an application liquid which contains a photo-curing resin is supplied to a surface of a substrate from a nozzle which moves relative to the substrate, the application liquid is irradiated with UV light and accordingly hardened, and banks for running a wiring material are formed. As the wiring material which is a liquid material is allowed to run in a groove which is defined between the banks thus formed, a wiring pattern having a high aspect ratio is formed in the substrate surface.
However, those techniques which utilize application of an application liquid and irradiation of the application liquid with light to form a pattern have the following problems. That is, irradiating with light of the liquid as it has just been discharged from the nozzle is effective in order to harden the application liquid applied onto the substrate while maintaining the shape of the application liquid. If light is irradiated at a position immediately close to the nozzle however, the irradiation light could potentially cure and affix the application liquid around the discharge port of the nozzle and clog the discharge port. If the light is irradiated far from the nozzle in an effort to avoid this problem, the discharged application liquid runs spreading out before getting cured, making it impossible to obtain a desired cross-sectional shape. This problem is particularly apparent when the application liquid has a relatively low viscosity.
If the distance from the nozzle to a light emitter from which the light is irradiated toward the application liquid is long, the light could not sufficiently irradiate the rear end of the coating liquid when discharging of the application liquid from the nozzle has just finished at an application end position, in which case curing becomes inadequate and the shape of the pattern becomes deformed.
With the conventional pattern forming techniques, it is thus difficult to prevent the application liquid from hardening and adhering to the nozzle while at the same time allowing the applied application liquid to harden without fail.